The present invention relates to an integrated circuit for driving inductive loads.
As is known, integrated circuits which use a P-type substrate require that said substrate be biased at the lowest voltage of the circuit so that the different epitaxial wells or regions which contain the active and passive components of the circuit are isolated from one another. In fact, the P-N junctions which form between the substrate and the different epitaxial wells are inversely biased and ensure an effective electrical isolation of said various wells.
It is furthermore known that in integrated circuits for driving inductive loads having a terminal connected to the earth (and thus hereinafter also defined as "loads" referred to earth), when the current supplied to the load is suddenly interrupted, a negative overvoltage is created across the latter. Accordingly, if the substrate, as occurs presently, is clamped to the ground, the epitaxial well or tubs connected to the load reaches a voltage lower than that of the substrate. In this condition said substrate injects current in the epitaxial well entailing a whole series of problems, such as for example the undesired activation of other components of the circuit.
To solve this problem, different solutions have already been studied, in particular to create preferential current paths to collect the current injected by the epitaxial well at negative voltage. However such solutions are not free from disadvantages, for example they are not applicable in all the required cases.